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customer.io

https://customer.io· First analyzed 10 Apr 2026· Updated 10 Apr 2026
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customer.io
Desktop screenshot of customer.io
Mobile screenshot of customer.io
Mobile

Sponsored

Hosting Provider

Vercel
vercel.com

IP Address

76.76.21.21

Site Location

🇺🇸 Beaverton, United Statesvia schema_nap

Server Location

🇺🇸 Walnut, United States

ASN

AS16509

Organization

Vercel, Inc

Server

Vercel

Nameservers

ns-1893.awsdns-44.co.uk.ns-499.awsdns-62.com.ns-618.awsdns-13.net.ns-1181.awsdns-19.org.

Performance

100

Core Web Vitals

Weight

First Contentful Paint
432 ms10%
Speed Index
562 ms10%
Largest Contentful Paint
—25%
Total Blocking Time
0.0 ms30%
Cumulative Layout Shift
0.00025%
1.2 MB
126 requests

Image Optimization

Lazy LoadResponsiveVercel Image Optimization
0–49
50–89
90–100

Architecture Stack

JAMstack
🔀 Hybrid
Decoupled
Frontend
Framework
Next.js
Styling
Tailwind CSS
API
Data Source
Headless CMS
Sanity
Infrastructure
Platform
Vercel
CDN
Vercel Image

Progressive Web App

Web ManifestApple Touch IconTheme Color

Detected API Sources

/_next/image?url=https%3A%2F%2.../_next/image?url=https%3A%2F%2...

Technology Stack

12 Technologies Detected

Analytics

3
Google Analytics
Google Analytics 4
Microsoft Clarity

Advertising

3
Twitter AdsLinkedIn AdsMicrosoft Advertising

CSS Frameworks

2
Tailwind CSS
Ant Design

Meta Frameworks

1
Next.js

Other

1
Lottie

Tag Managers

1
Google Tag Manager

Platforms

1
Vercel

SEO Analysis

A82/100
25
6
0
Meta Tags15/15
Content8/12
Headings8/8
Technical24/25
E-E-A-T7/7
Images4/7
Links2/5
URL5/5
Social5/5
Freshness0/4
Mobile1/4
Indexability3/3
C
customer.iocustomer.io

Customer.io Platform: Automation, Data, Content Creation

Explore Customer.io, the data-driven platform for personalized customer journeys across all channels, fueled by first-party data.

Title Length56 chars

Recommended: 50-60 chars (~338px / 580px)

Description Length129 chars

Recommended: 120-160 chars

Issues (0)

    6 issues found

    Upgrade to view details

    Crawlability

    Sitemap

    Type: standard

    439 URLs

    robots.txt

    9 rules

    Sitemap reference found

    Local SEO

    Local Search Readiness

    34/100
    Needs Work
    9 12

    Sponsored

    AI & LLM Readiness

    D52/100
    Bot Access
    20/25
    Machine Read.
    13/25
    Schema Data
    6/25
    Citation
    13/25

    AI Bot Access

    14/14 accessible
    AI Search
    OAI-SearchBot
    PerplexityBot
    Claude-SearchBot
    Gemini-Deep-Research
    DuckAssistBot
    Training
    GPTBot
    ClaudeBot
    Google-Extended
    Meta-ExternalAgent
    Bytespiderinfo
    Amazonbot
    Applebot-Extended
    CCBotinfo
    Fetch
    ChatGPT-User

    Machine Readability

    llms.txt
    llms-full.txt
    Semantic HTML
    Heading Hierarchy
    nav
    Text ratio:1%
    Words:714
    Token eff.:Optimal
    Sections/1K:8.4
    Depth:1/5

    Structured Data

    1 JSON-LD
    Person×1.3Organization×1.1
    sameAs entity links

    Citation Readiness

    Opening Summary43w
    Descriptive Headingsavg 2.3w
    Canonical URL
    Open Graph3/3
    Twitter Card3/3
    Language Tag
    Publish Date
    Author Info
    Lists
    Tables
    TL;DR / Summary
    About Page Link
    Recommendations (6)
    AI readiness recommendation preview...
    Upgrade to view recommendations

    Sponsored

    Accessibility

    WCAG 2.1 Compliance

    Evaluates how accessible your website is for users with disabilities, based on WCAG 2.1 guidelines. Checks images, forms, keyboard navigation, ARIA roles, and color contrast.
    A
    80/100
    12
    Passed
    2
    Critical
    1
    Warnings
    Images & Alt Text
    20/20
    Checks if images have descriptive alt text for screen readers and visually impaired users.
    Semantic Structure
    20/20
    Evaluates proper use of HTML5 semantic elements (header, nav, main, footer) and heading hierarchy.
    Forms & Inputs
    15/15
    Verifies form fields have labels, error messages are clear, and inputs are properly associated.
    Color & Contrast
    15/15
    Tests text-to-background color contrast ratios against WCAG AA/AAA minimum requirements.
    Keyboard & Focus
    6/15
    Ensures all interactive elements are reachable and operable via keyboard (tab, enter, escape).
    ARIA & Roles
    4/15
    Checks correct use of WAI-ARIA attributes (roles, states, properties) for assistive technologies.
    2 recommendations
    • •Accessibility recommendation preview...
    Upgrade to view recommendations

    Carbon Footprint

    SWDM v4 · Eco-Score

    Carbon emissions estimated using the Sustainable Web Design Model v4 (SWDM v4). Factors in data center, network, and device energy across new and returning visitors. Grade thresholds based on HTTP Archive percentiles.
    63/100
    B
    122 mg
    CO₂e / view
    1.2 MB
    Page Weight
    70%
    Cleaner Than
    New Visitor
    139 mg
    vs
    Returning (cached)
    69 mg
    Annual (10K/mo)
    14.6 kg
    Emission Segments
    Data Center
    6 mg
    Network
    36 mg
    Device
    80 mg
    Resource Breakdown
    JavaScript
    749.7 KB
    Images
    11.3 KB
    CSS
    49.8 KB
    Fonts
    89.9 KB
    HTML
    58.7 KB
    Other
    243.8 KB
    Green Hosting Verified
    Vercel
    Provider Match
    4 recommendations
    • •Carbon footprint recommendation preview...
    Upgrade to view recommendations
    B

    Security Score

    76%Good
    Static / Informational

    HTTPS

    No WAF

    40d

    Certificate Details

    Type

    Domain Validated (DV)

    Certificate Authority

    Let's Encrypt

    Key Algorithm

    RSA (2048 bit)

    Signature

    SHA-256 with RSA

    TLS Version

    TLSv1.3

    HTTP Protocol

    HTTP/2

    Valid From

    20.02.2026

    Valid Until

    21.05.2026

    Subject Alternative Names (1)

    customer.io

    SHA-256 Fingerprint

    F8:05:05:9B:A6:B0:C8:5B:0A:84:08:2C:0A:F6:3B:2A:D9:18:CD:A9...

    Recommendations

    Security recommendation preview

    Upgrade to view recommendations
    Upgrade to view header details

    HTTP Headers

    Developer Console

    access-control-allow-headers
    next-router-prefetch, Content-Type, Authorization
    access-control-allow-methods
    GET, POST, PUT, DELETE, OPTIONS
    access-control-allow-origin
    *
    age
    229
    cache-control
    🟡 0s(public, max-age=0, must-revalidate)
    content-encoding
    ⚡ Brotli(br)
    Good Warning Issue

    Email Infrastructure

    Google Workspace

    Score

    93

    SPF
    DKIM
    DMARC

    DMARC Policy

    Quarantine (Moderate)

    MX Records (5)

    aspmx2.googlemail.com
    aspmx3.googlemail.com
    alt2.aspmx.l.google.com
    alt1.aspmx.l.google.com

    +1 more

    Domain Information

    customer.io

    Domain Age
    14y 5m

    Created

    26.10.2011

    Expires

    26.10.2026

    Last Updated

    26.11.2025

    Registrar

    1API GmbH

    DNSSEC
    Not Enabled

    Privacy & Compliance

    Cookiebot

    Cookie Consent Banner
    Cookiebot
    Privacy Policy
    Terms of Service

    GDPR Indicators

    Cookie consent banner detected
    CMP: Cookiebot
    Privacy policy page linked
    Data Protection Officer mentioned

    Mobile Compatibility

    Viewport & Responsive Test

    Tests how well your website works on mobile devices. Checks viewport configuration, responsive layout, touch targets, font readability, and simulates rendering across different screen sizes.
    A
    81/100
    Mobile Friendly2 breakpoints
    Viewport Meta
    The viewport meta tag tells mobile browsers how to scale the page. Without it, mobile devices render at desktop width.
    Responsive Design
    Uses CSS media queries or flexible layouts to adapt content to different screen sizes automatically.
    Touch Icons
    Apple touch icons and favicons displayed when users add the site to their home screen on mobile devices.
    Readable Font Size
    Base font size should be at least 16px on mobile to ensure text is readable without zooming.
    Relative Units
    Using em, rem, %, or vw instead of fixed px values allows content to scale properly across screen sizes.
    No H-Scroll Risk
    No elements wider than the viewport that would cause horizontal scrolling on mobile devices.
    Tap Targets OK
    Interactive elements (buttons, links) are at least 48x48px with enough spacing to prevent accidental taps.
    No Fixed Widths
    No elements with fixed pixel widths that could overflow on smaller screens and break the layout.
    Viewport
    width=device-width, initial-scale=1
    1 recommendation
    • •Mobile compatibility recommendation preview...
    Upgrade to view recommendations

    Typography & Readability

    saansFont

    WCAG AA
    79/100
    Readability
    /30
    20/30

    14px · LH 1.40

    Hierarchy
    /20
    17/20

    5.29x ratio · ✓ H1→H6

    WCAG
    /25
    22/25

    5.43:1 min contrast

    Performance
    /25
    20/25

    1 font · 1 req

    Heading Font

    saansFont

    Sans74px

    Body Font

    saansFont

    Sans14px

    Contrast Ratio

    5.43:1

    WCAG AA (≥4.5:1)

    Reading Comfort

    ~34 CPL

    Narrow lines
    74px
    h1
    48px
    h2
    30px
    h3
    14px
    p

    ⚠️ Small text: 14px may strain on mobile. Use ≥16px for WCAG compliance.

    ✅ Optimal line spacing: 1.40 ratio (ideal range 1.4–1.6).

    ⚠️ Hard to read: Flesch score 43/100. Simplify sentences for wider reach.

    ✅ WCAG AA contrast: All text meets 4.5:1 ratio (min 5.4:1).

    ✅ Perfect heading hierarchy: Sequential h1→h2→h3 with single H1 — ideal for SEO & accessibility.

    ✅ Strong hierarchy: Headlines are 5.3x larger than body text.

    Buy on MyFontsFlesch 43

    Color Palette

    6 unique colors
    11.52:1 AAA Light
    #ffffff
    Background· 82.99999999999999%
    #39393b
    Other· 8.1%
    #d7dfda
    Primary· 2.1%
    #111e22
    Secondary· 1.4%

    Business & Marketing Stack

    8 Tools Detected

    Enterprise

    Behavior Analytics

    3
    Google AnalyticsFree
    Microsoft ClarityFree
    Google Tag ManagerFree

    User behavior and product analytics

    Advertising

    4
    Twitter/X AdsMid-Market
    LinkedIn AdsEnterprise
    Microsoft AdsEnterprise
    Reddit PixelMid-Market

    Ad platforms and retargeting pixels

    Privacy & Cookies

    1
    CookiebotMid-Market

    Cookie consent and privacy compliance tools

    3

    Categories

    8

    Total Tools

    2

    Enterprise

    3

    Mid-Market

    Assessment: Sophisticated marketing and sales technology infrastructure

    Sponsored

    Scripts & Styles

    22 Resources

    20
    Scripts
    2
    Styles
    20
    Async
    0
    Defer

    Top Script Sources

    local(5)googletagmanager.com(3)google-analytics.com(2)consent.cookiebot.com(2)scripts.clarity.ms(1)

    Website Identity

    Customer.io Platform: Automation, Data, Content Creation

    14 years old

    9450 SW Gemini Dr, Beaverton

    Beaverton

    US

    Location detected: 🇺🇸 United States, Beavertonvia schema_nap
    1API GmbH📧 Google Workspaceen

    Sponsored

    Last analyzed: 10 Apr 2026 at 14:21

    AI-Powered Analysis

    Technical Deep Dive

    Technology Analysis for customer.io

    StackOptic has analyzed this website's technology stack. View the detailed breakdown in the sections above.

    Analysis by StackOptic AIApr 10, 2026

    AI-Powered Insights

    Historical Analysis & Change Tracking